CVE-2026-101202 in Image Viewer
Summary
by MITRE • 09/29/2026
A flaw has been found in FastStone Image Viewer up to 8.3. The affected element is an unknown function of the component TGA Image Handler. Executing a manipulation can lead to out-of-bounds write. It is possible to launch the attack remotely. The vendor was contacted early about this disclosure but did not respond in any way.
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Analysis
by VulDB Data Team • 09/29/2026
The vulnerability identified in FastStone Image Viewer versions up to 8.3 represents a critical security risk within its TGA image handling component, specifically affecting an unknown function responsible for processing Truevision Advanced Graphics Adapter (TGA) files. This flaw is classified as an out-of-bounds write, which falls under the Common Weakness Enumeration category CWE-787: Out-of-Bounds Write. Unlike buffer overflows that may only allow for memory corruption leading to code execution through stack smashing or heap spraying techniques in some contexts, an out-of-bounds write specifically involves writing data beyond the allocated boundaries of a buffer. This type of vulnerability is particularly dangerous because it can corrupt adjacent memory structures, overwrite control flow data such as return addresses or function pointers, and ultimately lead to arbitrary code execution with the privileges of the affected application. The presence of this flaw in an image viewer highlights the persistent risk associated with parsing complex file formats where input validation may be insufficient against malformed or maliciously crafted inputs designed to trigger specific edge cases within the parser logic.
The operational impact of this vulnerability is severe due to its remote exploitability, which aligns with the MITRE ATT&CK technique T1203: Exploitation for Client Execution. Attackers can leverage social engineering tactics by distributing specially crafted TGA files through email attachments, instant messaging platforms, or compromised websites hosting malicious images. When a victim opens the malformed file using FastStone Image Viewer, the application processes the input without adequate bounds checking, allowing an attacker to write data into unintended memory locations. This capability enables the execution of arbitrary code on the target system, potentially resulting in full system compromise, installation of malware, establishment of persistent backdoors, or exfiltration of sensitive data stored locally. The fact that the vendor did not respond to early disclosure attempts exacerbates the risk landscape, as it suggests a lack of timely patching and leaves users exposed for an extended period without official remediation guidance from the software provider.
From a technical perspective, mitigating this vulnerability requires both immediate user-side precautions and broader industry awareness regarding image parsing security. Users should immediately cease using FastStone Image Viewer until a patched version is released or consider switching to alternative applications with more robust security practices and active maintenance cycles. It is also advisable to disable automatic previewing of images in file explorers, as this can trigger the vulnerability without explicit user interaction beyond viewing a directory listing. For organizations deploying this software, implementing application whitelisting policies can prevent unauthorized execution of potentially compromised binaries. Furthermore, network-level controls such as deep packet inspection or content security gateways that scan for malformed image files before they reach end-user devices provide an additional layer of defense against exploitation attempts. The broader industry must recognize the importance of secure coding practices in multimedia libraries and advocate for responsible disclosure timelines to ensure vulnerabilities are addressed promptly rather than left unpatched due vendor non-responsiveness.